Proving It - A Review of 80 Published Field Studies Demonstrating the Importance of Increased Fracture Conductivity

摘要

Many engineers disregard laboratory reports demonstratingthat the pressure losses across proppant samples aresubstantial. Similarly, it appears that the modeling studieswarning of substantial productivity losses due to inadequatefracture conductivity have not been universally convincing.Perhaps many practical frac engineers simply object to thetheoretical nature of these arguments, when they quote one ofthe more influential orators of our time, Shania Twain,1stating, “That don’t impress me much.”Instead, many Petroleum Engineers prefer to see theeconomic benefit demonstrated in real reservoirs, andseemingly borrow a quotation from the film Jerry Maguire,2stating, “Show me the money!”The purpose of this paper is to summarize the results ofover 80 field studies where well productivity was improvedby increasing the fracture conductivity. The benefit ofincreased conductivity has been demonstrated in oil,condensate, and gas reservoirs in 50 regions around the globe.This benefit was documented by 250 authors representing over70 companies. Increased conductivity has been shown to bebeneficial in oil wells producing 2 bopd to 25,000 bopd, and ingas wells producing less than 1 MMCFD to over 100MMCFD. Higher conductivity fractures were proven toimprove the cash flow in carbonates and sandstones at depthsof 2800 to 20,000 feet, and in low rate coal bed methane wellsshallower than 1500 feet.This review of industry experiences in a wide variety ofreservoirs is not presented as a substitute for a comprehensiveoptimization study in a specific location. Instead, thefollowing summary demonstrates that well productivity andprofitability can frequently be improved with redesign ofhydraulic fractures, despite the failure of many existingproduction models to predict those benefits.These studies are presented to satisfy the following goals:1) To verify that the extreme pressure losses observed inthe laboratory and predicted by current fluid flowtheory are real, i.e., “Proving It”.2) To provide a list of fields, encompassing a widevariety of reservoir types, to assist engineerssearching for results from an analogous field.3) To provide a number of field studies to whichproduction models can be calibrated.4) To summarize the collective experience of over 250authors, and incorporate what they have learned intofuture fracture designs.5) To demonstrate the relationship between fractureconductivity, well productivity, and cash flow, i.e.,“Show me the money!”